Heaven's Plateau
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Heaven's Plateau clear sky chart from 2005-11-05 to 2017-08-12.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
67%
15124
29%
46496
26%
15087
71%
15087
41%
24711

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
59%
718
20%
2491
20%
716
63%
716
30%
1411
January16th to endNight
54%
768
25%
2496
23%
768
61%
768
28%
1513
February1st to 15thNight
55%
699
24%
2228
23%
697
61%
697
29%
1348
February16th to endNight
53%
632
24%
1895
22%
632
59%
632
29%
1179
March1st to 15thNight
52%
720
17%
2091
16%
720
56%
720
27%
1366
March16th to endNight
53%
768
20%
2034
14%
768
57%
768
30%
1329
April1st to 15thNight
55%
719
20%
1799
11%
719
58%
719
32%
1205
April16th to endNight
61%
720
24%
1800
13%
720
64%
720
43%
1080
May1st to 15thNight
68%
593
28%
1673
19%
593
71%
593
54%
818
May16th to endNight
73%
374
27%
1496
31%
374
76%
374
42%
657
June1st to 15thNight
79%
360
28%
1440
35%
360
83%
360
49%
588
June16th to endNight
88%
360
37%
1440
50%
360
90%
360
69%
462
July1st to 15thNight
95%
340
35%
1360
47%
340
95%
340
73%
427
July16th to endNight
91%
472
40%
1504
41%
442
92%
442
68%
575
August1st to 15thNight
90%
593
38%
1642
29%
590
90%
590
72%
721
August16th to endNight
93%
700
42%
1750
27%
700
93%
700
80%
792
September1st to 15thNight
92%
660
45%
1650
33%
660
93%
660
80%
744
September16th to endNight
85%
656
44%
1764
39%
656
87%
656
70%
802
October1st to 15thNight
71%
660
31%
1980
32%
660
75%
660
48%
995
October16th to endNight
74%
704
36%
2112
37%
704
78%
704
51%
1034
November1st to 15thNight
70%
700
30%
2270
30%
700
75%
700
42%
1167
November16th to endNight
59%
720
28%
2373
28%
720
64%
720
34%
1304
December1st to 15thNight
55%
720
22%
2520
19%
720
62%
720
26%
1494
December16th to endNight
45%
768
23%
2688
20%
768
53%
768
22%
1700

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
10%412212235%62%
47468
Night
11%312212335%60%
46688
TransparencyDay
25%27%18%24%19%
47148
Night
27%38%19%23%18%
46507
SeeingDay
14%12%32%27%9%4
5697
Night
13%310%33%31%8%
15133

By Month

Percentage Cloud Cover SW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
18%412313335%52%
1447
16th to endDay
20%9%13323235%44%
1728
February1st to 15thDay
18%7%13313336%47%
1625
16th to endDay
22%9%2431233440%
1579
March1st to 15thDay
18%9%2442445%5%38%
1866
16th to endDay
18%7%24423347%41%
2189
April1st to 15thDay
16%7%24423345%43%
2149
16th to endDay
14%313212235%57%
2160
May1st to 15thDay
7%312212246%64%
2271
16th to endDay
9%413324245%57%
2615
June1st to 15thDay
5%213213235%65%
2520
16th to endDay
2111113282%
2520
July1st to 15thDay
1111112284%
2520
16th to endDay
11111112382%
2558
August1st to 15thDay
111112384%
2222
16th to endDay
1111122284%
2100
September1st to 15thDay
1111112384%
1980
16th to endDay
3212122478%
1862
October1st to 15thDay
7%212212347%63%
1650
16th to endDay
9%21222244463%
1760
November1st to 15thDay
10%413323348%54%
1587
16th to endDay
13%5%14422335%52%
1584
December1st to 15thDay
19%7%1342323447%
1440
16th to endDay
23%6%23323335%41%
1536
January1st to 15thNight
16%5%1331335%6%49%
2491
16th to endNight
18%5%13323335%48%
2496
February1st to 15thNight
17%5%14322448%44%
2227
16th to endNight
20%6%24213345%45%
1895
March1st to 15thNight
19%8%23423346%43%
2091
16th to endNight
19%5%12323336%46%
2034
April1st to 15thNight
15%6%24434445%44%
1799
16th to endNight
12%31331335%6%57%
1800
May1st to 15thNight
7%11111235%7%65%
1673
16th to endNight
6%312211336%64%
1496
June1st to 15thNight
4311212345%71%
1440
16th to endNight
111212284%
1440
July1st to 15thNight
11222284%
1440
16th to endNight
2211221382%
1608
August1st to 15thNight
111111212281%
1651
16th to endNight
11213384%
1750
September1st to 15thNight
11112286%
1650
16th to endNight
21111211380%
1764
October1st to 15thNight
6%212312335%66%
1980
16th to endNight
7%11212336%66%
2112
November1st to 15thNight
10%312213336%60%
2270
16th to endNight
13%413323335%54%
2373
December1st to 15thNight
19%5%13323336%47%
2520
16th to endNight
24%6%13322335%42%
2688

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
34%39%21%18%10%
1447
16th to endDay
43%37%14%18%12%
1728
February1st to 15thDay
39%38%21%19%7%
1625
16th to endDay
48%37%23%14%2
1579
March1st to 15thDay
46%411%15%16%5%
1866
16th to endDay
42%6%14%18%13%3
2189
April1st to 15thDay
41%412%22%15%4
2149
16th to endDay
29%313%26%21%5%
2160
May1st to 15thDay
20%210%30%28%6%
2271
16th to endDay
28%312%27%21%6%
2619
June1st to 15thDay
20%310%22%23%19%
2520
16th to endDay
9%1314%35%35%
2520
July1st to 15thDay
7%127%27%53%
2371
16th to endDay
9%1310%25%49%
2399
August1st to 15thDay
8%1210%30%46%
2206
16th to endDay
7%111%39%38%
2100
September1st to 15thDay
8%139%39%37%
1980
16th to endDay
12%1422%36%21%
1862
October1st to 15thDay
20%38%22%27%17%
1650
16th to endDay
23%36%24%26%15%
1760
November1st to 15thDay
29%310%23%21%11%
1587
16th to endDay
35%37%19%27%6%
1584
December1st to 15thDay
42%28%20%19%6%
1440
16th to endDay
44%310%15%15%9%
1536
January1st to 15thNight
34%49%21%19%10%
2491
16th to endNight
38%47%13%18%17%
2496
February1st to 15thNight
38%38%21%19%9%
2238
16th to endNight
39%310%26%16%4
1895
March1st to 15thNight
41%5%10%16%18%6%
2091
16th to endNight
39%5%11%20%17%5%
2034
April1st to 15thNight
39%5%12%22%15%4
1799
16th to endNight
27%5%12%27%18%7%
1800
May1st to 15thNight
18%312%27%28%10%
1674
16th to endNight
21%313%30%22%8%
1496
June1st to 15thNight
15%412%22%24%20%
1440
16th to endNight
9%315%34%36%
1440
July1st to 15thNight
6%128%24%55%
1360
16th to endNight
10%129%22%52%
1504
August1st to 15thNight
10%1212%27%46%
1642
16th to endNight
7%1110%37%42%
1750
September1st to 15thNight
7%129%38%39%
1650
16th to endNight
11%1223%38%22%
1764
October1st to 15thNight
21%36%22%28%16%
1980
16th to endNight
19%36%23%29%17%
2112
November1st to 15thNight
25%410%22%22%14%
2270
16th to endNight
31%37%21%25%9%
2373
December1st to 15thNight
39%39%21%17%9%
2520
16th to endNight
44%38%14%18%10%
2688

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
44%126%20%5%2
75
16th to endDay
28%7%23%23%11%4
256
February1st to 15thDay
25%11%26%23%10%2
245
16th to endDay
28%16%24%20%10%
238
March1st to 15thDay
27%19%21%19%9%2
270
16th to endDay
25%20%29%17%7%1
288
April1st to 15thDay
26%21%30%14%5%1
269
16th to endDay
19%25%28%19%5%1
270
May1st to 15thDay
14%19%37%19%6%2
288
16th to endDay
16%15%23%28%10%5%
330
June1st to 15thDay
8%16%37%25%6%5%
315
16th to endDay
37%39%33%6%8%
315
July1st to 15thDay
1337%41%6%9%
305
16th to endDay
2240%37%9%7%
327
August1st to 15thDay
2448%30%9%5%
300
16th to endDay
1443%35%8%7%
268
September1st to 15thDay
17%43%35%9%3
255
16th to endDay
6%10%29%40%11%1
255
October1st to 15thDay
8%14%36%29%9%2
255
16th to endDay
15%12%28%26%15%1
272
November1st to 15thDay
12%5%7%30%33%10%
93
16th to endDay
22%10%17%30%15%2
84
December1st to 15thDay
31%8%33%13%11%1
60
16th to endDay
26%420%21%15%10%
64
January1st to 15thNight
18%411%33%24%8%
720
16th to endNight
22%313%31%22%7%
768
February1st to 15thNight
19%312%34%23%5%
704
16th to endNight
23%6%11%32%20%6%
632
March1st to 15thNight
21%5%11%32%22%5%
720
16th to endNight
22%5%13%29%23%5%
768
April1st to 15thNight
19%412%36%23%3
719
16th to endNight
13%414%35%25%6%
720
May1st to 15thNight
8%415%39%28%4
594
16th to endNight
7%310%30%42%5%
375
June1st to 15thNight
5%18%37%41%5%
360
16th to endNight
1339%49%5%
360
July1st to 15thNight
128%62%7%
340
16th to endNight
3223%53%16%
472
August1st to 15thNight
2234%48%11%
593
16th to endNight
1336%49%9%
700
September1st to 15thNight
1334%47%12%
660
16th to endNight
217%34%40%14%
656
October1st to 15thNight
7%311%34%33%10%
660
16th to endNight
9%29%32%32%13%
704
November1st to 15thNight
12%29%34%31%10%
700
16th to endNight
15%413%33%25%7%
720
December1st to 15thNight
23%311%34%19%7%
720
16th to endNight
27%5%14%29%18%4
768
Page generated at 2017-08-13 11:16:25. Version ac04

Copyright 2017 A. Danko


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